It is well known that a synchronous electric motor converts AC electrical energy into synchronous rotational mechanical energy, i.e., shaft torque and rotation. Motor operation is based upon the motor effect, where a current carrying conductor experiences a force in a magnetic field. Control of such motors can be governed by motor controllers.
The motor controllers of the prior art include proportional-integral (PI) controllers such as illustrated in FIG. 2. Specifically, FIG. 2 depicts a standard, nested loop proportional-integral (PI) vector controller 100 of a PMSM. The outer speed loop 102 provides a reference for desired motor torque, immediately translated to the level of i.sub.q that would produce that torque. Two inner current loops 104, 106 are used to control the respective "d" and "q" current components. They each include a nonlinear feedback that removes the nonlinear back EMF of the static nonlinearity subsystem 108a, 108b, and thus decouple the two current components. PI compensators 110, 112, 114 are then used to drive i.sub.q to zero and i.sub.q to its reference value.
It is often desirable for the motor to change its speed in accord with a preselected speed profile. However, the controllers of the prior art--such as the controller 100 of FIG. 2--generally require that the current convergence rates of the controller are faster than the desired convergence rate of the motor speed reference. This often requires gain adjustments for operation over a wide range of speeds and torques.
It is, accordingly, an object of the invention to provide a dissipativity-based, non-linear motor controller which processes and sets primary and incremental drive voltages for synchronous motor drives.
Other objects will become apparent in the description which follows.